Coarse particles-water mixtures flow in pipes

0477911 - ÚH 2018 RIV RU eng J - Journal Article
Vlasák, Pavel
Coarse particles-water mixtures flow in pipes.
Journal of Mining Institute. Roč. 225, č. 2017 (2017), s. 338-341. ISSN 2411-3336. E-ISSN 2541-9404
R&D Projects: GA ČR GAP105/10/1574
Institutional support: RVO:67985874
Keywords : hydrotransport * coarse particles pipeline installation * pressure drop * pipe inclination
OECD category: Fluids and plasma physics (including surface physics)

The present paper is focused on evaluation of the effect of average mixture velocity and overall concentration on the pressure drop versus the slurry average velocity relationship, on slurry flow behaviour and local concentration distribution. The experimental investigation was carried out on the pipe loop of inner diameter D = 100 mm, which consists of smooth stainless steel pipes and horizontal, inclinable and vertical pipe sections. The frictional pressure drop in the horizontal pipe section were significantly higher than that in the vertical pipe due to the fact, that for stratified flow the contact load produced significant energy losses. The frictional pressure drop of coarse particles mixtures in vertical pipe increased with the increasing mixture concentration and velocity, what confirmed effect of inner friction, inter-particles collision, and the drag due to particle-liquid slip. It was found that for stratified coarse particles-water mixture the frictional pressure drop was not significantly influenced by the pipe inclination, especially for low concentration values. The effect of pipe inclination decreased with increasing mixture velocity in ascending pipe section: the maximum value was reached for inclination between 20 and 40 degrees. Inclination of pressure drop maximum increased with decreasing mixture velocity. In descending pipe section the frictional pressure drop gradually decreased with increasing pipe inclination. The effect of inclination on frictional pressure drops could be practically neglected, especially for low mixture concentration and higher flow velocities. The study revealed that the coarse particle-water mixtures in the horizontal and inclined pipe sections were significantly stratified. The particles moved principally in a layer close to the pipe invert. However, for higher and moderate flow velocities the particles moved also in the central part of the pipe cross-section, and particle saltation [ 1] was found to be dominant mode of particle conveying.
Supports under the project P105/10/1574 of the Grant Agency of the Czech Republic, and RVO: 67985874 of the Czech Academy of Sciences are gratefully acknowledged.
Permanent Link: http://hdl.handle.net/11104/0276255